Google has been improving its ability to identify manipulative links for decades in response to aggressive search marketers who keep inventing new ways to manufacture links.
In simple terms, search algorithms divide links into two kinds:
- Normal (natural) links
- Unnatural links
Unnatural links are essentially spam, and normal links are everything else.
The goal for Google is to ignore unnatural links and only count the natural links and use those for ranking purposes.
The problem for businesses is those old tactics that Google is aware of keep coming back with new names.
When that happens, spammy techniques that should be avoided gain popularity, and Google is already there to devalue them all over again.